In this paper, we define the task of Number Identification in natural context. We present and validate a language-independent semiautomatic approach to quickly building a gold standard for evaluating number identification systems by exploiting hand-aligned parallel data. We also present and extensively evaluate a robust rule-based system for number identification in natural context for Arabic for a variety of number formats and types. The system is shown to have strong performance, achieving, on a blind test, a 94.8% F-score for the task of correctly identifying number expression spans in natural text, and a 92.1% F-score for the task of correctly determining the core numerical value.